The Value of GRPR PET Imaging for Diagnosis and Staging in Prostate Cancer

January 16, 2026 updated by: First Affiliated Hospital of Fujian Medical University

The Value of Gastrin-Releasing Peptide Receptor (GRPR) PET Imaging for Diagnosis and Staging in Prostate Cancer

The gastrin-releasing peptide receptor (GRPR) is highly expressed in prostate cancer (77%-100%). Numerous studies have confirmed that GRPR PET imaging has emerged as a significant molecular imaging modality in prostate cancer, particularly serving as a complementary tool to PSMA PET for addressing cases with negative or insufficient PSMA expression. It demonstrates substantial value in initial staging (especially in intermediate- and high-risk patients), detecting sites of biochemical recurrence, assessing metastatic lesions (notably in mCRPC), and guiding treatment decisions. 68Ga-G21 and 68Ga-G23 are two novel molecular probes targeting GRPR. This study aims to evaluate their biodistribution and diagnostic performance in prostate cancer and compare them with 68Ga-PSMA-11 PET imaging.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The gastrin-releasing peptide receptor (GRPR), also known as the bombesin receptor subtype BB2, is a G protein-coupled receptor containing seven transmembrane domains. Its endogenous ligand, gastrin-releasing peptide (GRP), exhibits high homology at the C-terminal peptide sequence with bombesin (BBN), a 14-amino-acid peptide derived from amphibians. GRP regulates a series of physiological processes including cell proliferation, differentiation, and metabolism by activating GRPR and its downstream phospholipase C signaling pathway. Studies have shown that GRPR is highly expressed in various malignant tumors and their metastases, such as gastrinoma (100%), prostate cancer (77%-100%), glioma (85%), gastrointestinal stromal tumors (84%), and breast cancer (62%-71.9%), and is closely associated with tumor growth, invasion, and metastasis. Owing to its widespread and high expression across multiple tumor types, GRPR has emerged as a pan-cancer target of significant clinical value, demonstrating strong potential for applications in the fields of precise tumor diagnosis and targeted therapy. Numerous studies have confirmed that GRPR PET imaging has emerged as a significant molecular imaging modality in prostate cancer, particularly serving as a complementary tool to PSMA PET for addressing cases with negative or insufficient PSMA expression. It demonstrates substantial value in initial staging (especially in intermediate- and high-risk patients), detecting sites of biochemical recurrence, assessing metastatic lesions (notably in mCRPC), and guiding treatment decisions. 68Ga-G21 and 68Ga-G23 are two novel molecular probes targeting GRPR. This study aims to evaluate their biodistribution and diagnostic performance in prostate cancer and compare them with 68Ga-PSMA-11 PET imaging.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
6

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • China
    • Fujian
      • Fuzhou, Fujian, China, 350005
        • Recruiting
        • Department of Nuclear Medicine, First Affiliated Hospital of Fujian Medical University
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • confirmed treated or untreated prostate cancer patients;
  • signed written consent.

Exclusion Criteria:

  • known allergy against PSMA;
  • any medical condition that in the opinion of the investigator may significantly interfere with study compliance.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: 68Ga-G21 PET imaging
Intravenous injection of one dosage of 111-148 MBq (3-4 mCi) 68Ga-G21. Tracer of 68Ga-G21 will be used to image lesions of prostate cancer by PET imaging.
Drug: 68Ga-G21
Intravenous injection of one dosage of 111-148 MBq (3-4 mCi) 68Ga-G21. Tracer of 68Ga-G21 will be used to image lesions of prostate cancer by PET imaging.
Experimental: 68Ga-G23 PET imaging
Intravenous injection of one dosage of 111-148 MBq (3-4 mCi) 68Ga-G23. Tracer of 68Ga-G23 will be used to image lesions of prostate cancer by PET imaging.
Drug: 68Ga-G23
Intravenous injection of one dosage of 111-148 MBq (3-4 mCi) 68Ga-G23. Tracer of 68Ga-G23 will be used to image lesions of prostate cancer by PET imaging.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Number of participants with Imaging Emergent Adverse Events
Time Frame: From enrollment till 7 days safety follow-up
The distribution of adverse events (AE) will be done via the analysis of frequencies for imaging emergent Adverse Event, through the monitoring of relevant clinical and laboratory safety parameters.
From enrollment till 7 days safety follow-up
Dosimetry data
Time Frame: through study completion, an average of 3 months
Calculate the absorbed dose of 68Ga-G21 and 68Ga-G23 in normal organs.
through study completion, an average of 3 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Diagnostic value
Time Frame: through study completion, an average of 3 months
Sensitivity and Specificity of 68Ga-G21 and 68Ga-G23 PET imaging for prostate cancer in comparison with 68Ga-PSMA-11 PET imaging.
through study completion, an average of 3 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
First Affiliated Hospital of Fujian Medical University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Weibing Miao, MD, First Affiliated Hospital of Fujian Medical University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 20, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 16, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 16, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 23, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 23, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 16, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • FirstAHFujian-GRPR PET Imaging

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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